1. Technical Field
This disclosure relates to techniques for dehumidification and regeneration of compressed air, and, more particularly, to a regenerating-type compressed air drier.
2. Description of Related Art
With the rapid development of technology, compressed air is required to have improved quality, so as to ensure that the fabrication equipment has well enough availability. For example, the humidity of the compressed air is critical to the yield factor of a fabrication process. In recent years, researches are focused on the dehumidification of the compressed air.
An adsorption material that has dehumidification and regeneration capability is used to dehumidify the compressed air. The regeneration mechanism includes an indirect heating desorption method, a plasma desorption method, a microwave desorption method, and a low power consumption desorption method. The indirect heating method is performed in an air convention switching manner, which losses great heat. In the plasma desorption method, the regeneration process may be incomplete due to the varieties of the material characteristics, and an electric arc will be generated. The microwave desorption method employs microwaves to dehumidify the moisture of compressed air. However, the microwaves are easily to be blocked by a dehumidification structure and reduce the regeneration efficiency. In the low power consumption desorption method, water molecules are electrified to actuate the transitions of electrons. However, the low power consumption desorption method suffers from a low regeneration efficiency, because the adsorbent has poor conductivity and the currents generated are not evenly distributed. It is thus necessary to increase the power efficiency of the desorption regeneration.
A conventional drier may be designed in a variety of manners. A wheel-type drier comprises a dehumidification region, a regeneration region, and desiccant wheels that rotate cyclically between the dehumidification region and the regeneration region. High-humidity compressed air is guided into the dehumidification region for being dehumidified, and then the humidified compressed air is guided into an air storage barrel for storage. The desiccant wheels, once saturated, will rotate to the regeneration region, and processed in a desorption regeneration process by hot wind. The regenerated desiccant wheels will rotate to the dehumidification region again, ready for the next round of a dehumidification process. The wheel-type drier performs the dehumidification process and the regeneration process alternatively and continuously. The wheel-type drier employs a heater to generate heat needed to heat the regenerating air. However, this type of radiation and heat conduction suffers from a great energy loss and a low efficiency.
Another conventional drier comprises two adsorption towers and adsorbents filled in the adsorption towers. High-humidity compressed air is guided into one of the towers for the adsorbent therein to adsorb moisture contained in the compressed air. The humidified compressed air is guided into an air storage barrel for storage. At the same time, the adsorbent in the other of the towers is saturated with moisture, and the moisture can be desorbed from the adsorbent by heating the adsorbent. The heat can be transferred to the adsorbent by radiation or convention mechanism or a solid heat material. In this way, the adsorbent is regenerated, and is ready for adsorbing moisture of another high-humidity compressed air. However, this type of conventional drier, in which one of the adsorption tower is executing a dehumidification function, the other is executing a regeneration function, and heat is transferred to the adsorbent in a convention manner, consumes huge power. This type of conventional drier also needs a control valve to control the flowing mechanism of the compressed air, and therefore has a high manufacturing cost.
Therefore, how to provide a drier that consumes less power, performs better dehumidification efficiency, and has a lower manufacturing cost, is becoming an urgent issue in the art.